The attachment of pipes, for example, steam lines, feedwater lines and the like, to a vessel is commonly accomplished by the use of a separately formed annular sleeve or nozzle welded between the vessel and the pipe, the nozzle providing, in effect, a reinforcement of the vessel-to-pipe connection.
In some instances it is desirable to provide in-service inspection of the welds and other portions of such connections to verify their integrity or to discover any incipient defects so that appropriate repairs can be made before failure occurs.
In some cases, for example, where the vessel is relatively inaccessable or hazardous to humans, the use of conventional inspection techniques and equipment is undesirable or even impossible. A notable example is a pressure vessel containment for a nuclear reactor. Such a pressure vessel may be in the order of 60 feet in height and 20 feet in diameter with walls of steel 4 to 12 inches in thickness with a number of pipes, for example, from 4 inches to 28 inches in diameter connected thereto. In use, such a vessel and the adjacent portions of the pipes and the attachment nozzles are exposed to radioactive fields. Furthermore, such vessels are ordinarily closely surrounded (for example, as closely as 8 inches) by heat insulation and a biological shield wall. Limited access to the pipe attachment nozzles is usually provided by ports through which the pipes penetrate the shield wall, the space between the pipe and the port being normally closed by a shield door, hatch, shield blocks or the like. Thus, the foregoing conditions make it desirable to provide in-service inspection equipment which can be quickly installed and removed and which can be remotely operated to perform the desired examination. No previously known devices or equipment suitable to accomplish this purpose have been found.
It is an object of this invention to provide apparatus for the examination of the pipe attachments to a vessel which apparatus can be readily installed and removed and remotely controlled.